Effect of different concentrations of lysine on the transglutaminase-induced mixed surimi gel properties

The effect of different content of lysine (Lys, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, m/m) on the texture characteristics and water holding capacity (WHC) of transglutaminase (0.4%)-induced mixed surimi gels was explored. The results showed that 0.2% Lys obviously improved the gel strength, textural properties, and WHC of the mixed surimi gels (P < 0.05). However, superfluous Lys (0.4%–0.5%) played a significant negative impact. That’s because 0.2% Lys facilitated the non-covalent interactions and non-disulfide covalent interactions between surimi proteins, promoted the formation of a fine and dense gel microstructure. While high content of Lys induced the formation of excess ε-(γ-Glu)-Lys isopeptide bonds but weakened the non-covalent interactions between surimi proteins, resulting in an irregular and heterogeneous microstructure with large voids. In conclusion, moderate Lys can effectively improve the quality of mixed surimi gels, thereby providing a new and effective strategy to develop phosphorus-free surimi products.